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Magnetic nanoparticles with unique magnetic properties, such as superparamagnetic and high saturation magnetization, etc., and good biocompatibility, toxicity, in targeted drug delivery, magnetic resonance imaging, cellular and biomolecular separation, immune testing and other biomedical field has broad application prospects, so much the people favor in recent years. In order to broaden the magnetic nanoparticles in various fields of application, people of various magnetic nanoparticles surface modified in order to achieve its functional. According to the literature on the optical modification of magnetic nanoparticles prepared in a magneto-optical dual functional nanomaterials with excellent magnetic and optical properties, in magnetism, fluorescence, biology and medicine and other fields are widely used, especially in the ultra-high density information storage , bio-molecular recognition, drug delivery, and so has an attractive prospect. This paper studies Fe3O4, CoFe2O4 magnetic nanoparticles prepared, silica parcels and luminescent material modification, and the application of the MRI. The full text chapters. Chapter I outlines Magnetic Nanomaterials, modification and application prospects, core-shell structure of magnetic nanoparticles / silica composite nano-materials and nano-optical dual-function materials preparation and application and proposed thesis vision. Chapter II by chemical co-precipitation method with FeCl3 ยท 6H20 and FeCl2.4H2O as raw materials, ammonia as precipitant, first in different types of alcohol - Water System Preparation of Fe3O4 nanoparticles with TEM, XRD products were characterized. The results show that the morphology of the obtained nanoparticles with alcohol - water system changes polarity and viscosity spherical to rod-like structure by the transition, and particle size increases, the dispersion is improved. These nanoparticles can be stably dispersed in water. With oleic acid as surfactant to ethanol - water system Fe3O4 nanoparticles prepared by surface modification, the modified found after improving nanoparticle dispersion, and can be transferred from the aqueous phase to the organic phase. Followed by citric acid as a surfactant, can be prepared in water, stable dispersion of magnetic Fe3O4 nanoparticles. This Fe3O4 nanoparticles saturation magnetization Ms of 50.2 emu / g, a good superparamagnetic. Experimental studies have shown that magnetic resonance imaging, preparation of iron oxide nanoparticles with a larger transverse relaxation coefficient r2 (119.74 Fe mM-1s-1) and longitudinal relaxation coefficient r1 (13.64 Fe mM-1s-1), so The Fe3O4 nanoparticles either as T2 contrast agent, but also as a T1 contrast agent; Then, we thus Fe3O4 nanoparticle seeds, in Triton X-100 / hexanol / cyclohexane / water microemulsion system, using base-catalyzed hydrolysis of TEOS, condensation, prepared with a core-shell structure Fe3O4 @ SiO2 composite nanoparticles. Studied the mixing method, TEOS concentration on Fe3O4 @ SiO2 nanoparticle morphology. The results showed that the use of mechanical agitation can effectively control the morphology of the composite nanoparticles, and the formation of good dispersion of the core-shell morphology of the spherical nanoparticles. With increasing concentration of TEOS, SiO2 shell thickness, the composite particles are more uniform morphology. Finally, Fe3O4 @ SiO2 nanoparticles by modifying the 3 - aminopropyl triethoxysilane (APTES) to the surface of amino-functionalized, then the amino group with a silane coupling agent, small organic molecules form dansyl chloride alkylene dansyl light amine group, thereby synthesizing optical dual function Fe3O4 @ SiO2 @ APTES-Dy nanocomposites. Using TEM, FT-IR, UV-vis, XRD, XPS and other techniques were used to characterize the product obtained and studied the magnetic properties of materials and optical properties. In order to examine the material in biology, medicine feasibility of the application, we nanocomposite Fe3O4 @ SiO2 @ APTES-Dy carried out cytotoxicity tests and magnetic resonance imaging (MRI) study. The results showed that, Fe3O4 @ SiO2 @ APTES-Dy has a better effect of magnetic resonance imaging and cytotoxic small, is an excellent MRI T2 contrast agent. TEM cell biopsy showed composite nanoparticles can pass through the cell membrane into Hela cells endosomes and cytoplasm. The third chapter, we try to co-precipitation method, hydrothermal method, three methods were prepared by thermal decomposition of cobalt ferrite nanoparticles. Wherein the chemical coprecipitation of cobalt ferrite nanoparticles are water soluble, but although the larger particle size is not conducive to silica-coated, but also limits its application in biological aspects. Hydrothermal Synthesis of cobalt ferrite nanoparticles are mainly divided into two types, some of which are smaller nanoparticles into spherical, better dispersion; another part of the big flower-shaped nanoparticles by several small cobalt ferrite nanoparticle combination. CoFe2O4 nanoparticles saturation magnetization Ms of 53.2 emu / g, a good superparamagnetic. Experimental studies have shown that magnetic resonance imaging, Solvothermal of CoFe2O4 nanoparticles transverse relaxation coefficient r2 is 36.54 FemM-1s-1, can be used as T2 imaging contrast agents. Prepared by thermal decomposition of cobalt ferrite nanoparticles smaller particle size, the average particle diameter of about 5nm, coated with silica can easily be obtained monodisperse core-shell structure CoFe2O4 @ SiO2, changing it from an oil-soluble water-soluble. After ferrite coated silica nanoparticles by modification of drilling to amino-functionalized silane coupling agent, and the surface of the amino group using dansyl chloride luminescent dyes, optical bi-functional nano-particles to form CoFe2O4 @ SiO2 @ APTES- Dy. using a variety of electron microscopy and spectroscopy techniques resulting nanocomposites were characterized and studied their cytotoxicity and MRI imaging. The results show that nanocomposite CoFe2O4 @ SiO2 @ APTES-Dy has better magnetic resonance imaging and cytotoxic effects of smaller, is an excellent T2 magnetic resonance imaging contrast agents.
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